Several dozen protesters gathered in Madison, Wis., Friday night shortly after a police officer shot and killed a 19-year-old African American man who authorities say assaulted the officer during a struggle.

Madison Police Chief Mike Koval did not identify the slain man, who he said had attacked an officer who was responding to a complaint.

But the head of the local Boys & Girls Club, Michael Johnson — who met with Koval and said on social media that he had also met with the slain man's family — identified him as Tony Robinson.

Koval said investigators did not find a gun at the scene in an initial search.

The incident began about 6:30 p.m. when Madison police received calls about a man who had "battered someone" and had been "out in traffic" and then had gone into an apartment, Koval said in a televised news conference.

LAPD Sgt. Barry Montgomery said, "There is no evidence to support he was armed."

The man was shot by an officer sitting...

Investigators pored over a neighborhood in Burbank where a vehicle pursuit hours earlier concluded with a Los Angeles police officer fatally shooting a man early Thursday morning.

LAPD Sgt. Barry Montgomery said, "There is no evidence to support he was armed."

The man was shot by an officer sitting...

(Sarah Parvini, Joseph Serna and Irfan Khan)

Videos and photos on social media from Madison later Friday night showed a gathering of at least a couple of dozen demonstrators, some chanting anti-police slogans and carrying signs.

"The family has asked for peaceful protest," Johnson, executive officer of the Boys & Girls Club of Dane County, said on Twitter. He urged demonstrators to "remain calm."

Koval said that "in light of so much things that have happened not just across the country but in our own community," the reaction at the scene was "understandable" and "absolutely appropriate under the circumstances." He also called for calm.

Johnson said that Robinson had graduated from Sun Prairie High School and was about to attend Madison Area Technical College.

"He was loving and caring young man, according to his grandmother," Johnson said in a post on Facebook, showing Robinson in a graduation cap. "He wanted a business degree."

The shooting will be investigated by the state Department of Criminal Investigation, in accordance with a 2014 law that requires inquiries into such shootings to be handled by outside agencies.